Adult Still Disease

Adult-onset Still’s disease (AOSD) is a rare type of inflammatory arthritis that affects your whole body. It causes joint and muscle pain, a daily fever and a rash. It can also cause other systemic (whole-body) symptoms.

AOSD is an adult form of juvenile Still’s disease (juvenile idiopathic arthritis, JIA). It typically occurs in younger adults, between the ages of 16 and 35. Like JIA, the condition may be temporary, lasting less than a year, or may come and go for a long time. Symptom “flares” may occur regularly or far apart, and they may be mild to severe. Medications can help manage your symptoms when they arise.

Types of adult-onset Still’s disease

Adult-onset Still’s disease affects different people in different ways, and it’s hard to predict how it will affect you. But healthcare providers have observed that symptoms usually occur in one of three ways:

• Monophasic AOSD. Monophasic means there’s only one episode of symptoms, lasting weeks or months, but less than a year. This form may occur suddenly and go away just as suddenly.
• Polyphasic AOSD. Polyphasic means there are multiple episodes of symptoms. They occur periodically, weeks, months or years apart. They usually get shorter and less severe over time.
• Chronic AOSD. Chronic means that you have persistent symptoms or regular flares. Chronic AOSD is more likely to do progressive damage to your joints, as rheumatoid arthritis does.

Each of these types occurs with about equal frequency. But you can’t always tell which type it is right away. Sometimes, what seems to be monophasic or polyphasic AOSD later develops into chronic AOSD.